大学英语四级阅读200篇第9篇:转基因食品安全吗.doc.pdf
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1、2019 年 6 月大学英语四级阅读 200 篇第 119 篇:转基因食品安全吗 Is GM Food Safe To Eat?Traditional plant breeding involves crossing varieties of the same species in ways they could cross naturally.For example,disease-resistant varieties of wheat have been crossed with high-yield wheat to combine these properties.This type
2、 of natural gene exchange is safe and fairly predictable.Genetic engineering(GE)involves exchanging genes between unrelated species that cannot naturally exchange genes with each other.GE can involve the exchange of genes between vastly different species e.g.putting scorpion toxin genes into maize o
3、r fish antifreeze genes into tomatoes.It is possible that a scorpion toxin gene,even when it is in maize DNA1,will still get the organism to produce scorpion toxin but what other effects may it have in this alien environment?We are already seeing this problem adding human growth hormone genes to pig
4、s certainly makes them grow but it also gives them arthritis and makes them cross-eyed,which was entirely unpredictable.It will be obvious,for example,that the gene for human intelligence will not have the same effect if inserted into cabbage DNA as it had in human DNA but what side-effect would it
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